I have two C files, main.c and library.c, which contain the following:

// main.c
#include <stdio.h>

int MY_NUMBER = 6;

#include "library.c"

int main() {
    change_the_number();
    printf("The number: %dn", MY_NUMBER);
}

// library.c
void change_the_number() {
    MY_NUMBER = 5;
}

After running gcc main.c -o main, and then running main, I get the output The number: 5, which is exactly what I would expect.

VSCode underlines MY_NUMBER in library.c, complaining that “identifier MY_NUMBER is undefined”. This is also expected behaviour, as far as I’m concerned – looking solely at library.c, there’s nothing to indicate what MY_NUMBER is or where it comes from.

How can I configure Microsoft’s C/C++ extension to recognise MY_NUMBER?

What I’ve tried so far:

• Adding ${workspaceFolder} and ${workspaceFolder}/** to C-Cpp > Default: Include Path.
• Changing library.c to library.h (I didn’t really think this would do anything and I was right.)

One constraint is that I am unable to change the code – I must setup the IDE to allow for this declaration/usage arrangement, because I’m an intern and this pattern is repeated hundreds, if not thousands of times across the codebase I’m working on. I would ask my coworkers for help with this, but none of them use VSCode with C/C++ extension – every single one uses something different.

Ultimately, if the MS C/C++ extension doesn’t support this kind of thing, that’s fine, I’ll just use something else, but I thought it was interesting that this completely valid C program would flag up as problematic.